Numerical investigation on cooling effect in the circuit cabin of active cooling system of measurement-while-drilling instrument based on split-Stirling refrigerator

The thermal protection technology for high-temperature environment has made great progress in recent years. Restricted by the harsh environment of oil drilling, the design and development of measurement-while-drilling instrument (MWD) for high-temperature wells are still a worldwide issue. Although quite a few scholars have proposed a variety of thermal protection schemes, the feasibility or practical using effect has not been fully verified. Through comparative analysis of various cooling methods, it is considered that the active cooling scheme based on split-Stirling refrigerator is feasible, and a set of active cooling system is designed. The temperature distributions on the circuit cabin are presented. The influences of the structure parameters of circuit cabin, circuit board and refrigerator, the thermal conductivity of insulation material, the cooling power of refrigerator, the circuit board power, the annulus and water eye temperature on the cooling effect are discussed. The results show that the circuit board structure parameters, the insulation material thickness and thermal conductivity, the ratio between circuit board power and cooling power of split-Stirling refrigerator, the temperature difference between water eye and annulus are the key parameters affecting the cooling effect.